Thursday, October 10, 2013

Unidentified network problems

One of the
most annoying thing is sitting with a problem you know that you have solved
before but you do not remember the solution too anymore. That is just what I
now have spent the last 2 hours doing.

I am
sitting and testing out Windows Server 2012 R2 and DirectAccess feature, and suddenly
my domain controller are not reachable from any other computers on the network.
I only have one domain controller since I am using Microsoft Lab guide setup,
so this means nothing works. All other server and computer can communicate.
Some testing shows me that I can ping the server name but with IPv6 address
only, no response on IPv4. Checking out the network settings shows that the
«Network Location Awareness» service reports the network on the domain
controller as an «unidentified network» and automatically sets it up with a
«Public network» profile.

Well a
domain controller cannot do much when it is on a public network profile.
Therefore, I needed to fix this. Disabling and enabling the network card
actually got the profile on the network card set to the “Domain Network” and
the right domain name.

﻿

Problem solved?,
nope. Rebooting my client computer, I still get the “Public network” profile. I
restart the domain controller in case that there is something not started when
domain profile are activated late in the process. However, the reboot sets it
back to “Public network” profile, disabling and enabling fix it, but same
problem on client computer (and all my servers).

Sounds
great and this actually solved the profile selection problem on the domain
controller. However, this was actually just a symptom of the problem and not
the problem itself. Still no communication with domain controller from the
other computers.

Now it was
time to fight dirty, turning of the firewall to see if that helps, no.
Disabling IPv6, no. Then everything are pointing on IPv4 problem, and my tired
old brain starts to remember when I last had this problem on a Windows server
2008 R2 domain controller. I need to reset the IPv4 protocol.

Before
doing this, you should document your IP settings, so you can set it to the same
after the reset.

We need to
do this from a command prompt started with admin privileges, and a reboot.